1. Field of the Invention
The invention relates to doped silicon monocrystalline rods and somewhat more particularly to a process of producing phosphorous-doped silicon monocrystalline rods having a peripheral radial depletion or enrichment of the dopant therein.
2. Prior Art
Generally, it is desirable to produce silicon monocrystalline rods for use in manufacturing semiconductor components so that such rods have as homogeneous a dopant distribution as possible throughout the entire cross-section of the rod. However, in the manufacture of special semiconductor components, such as, for example, large-area power thyristors having a high reserve power rating, wherein one desires to insure that the reverse voltage and the blocking capacity are approximately equal, or large-area thyristors with an integrated three-layer diode wherein the breakdown voltage of the diode is below the trigger voltage of the thyristor, silicon crystals are used which have a homogeneous radial resistance (.rho.) profile or path in the center of the wafer or disc cut from such a rod and a preselect peripheral rise or drop in the electrical resistance profile at the edge of such wafer (i.e., silicon crystalline wafers having either a dish-shaped resistance profile or an inverse resistance profile). To attain such wafers, the monocrystalline rod must have a dopant distribution in the peripheral zones thereof which is lower or higher than the dopant distribution in the central zone thereof.